Post-Fatigue Fracture and Marginal Behavior of Endodontically Treated Teeth: Partial Crown vs. Full Crown vs. Endocrown vs. Fiber-Reinforced Resin Composite

Abstract

Objectives: To investigate in vitro post-fatigue fracture behavior of endodontically treated molars having been differently restored. Methods: A total of 120 extracted human molars were used. A total of 120 specimens in 14 test groups and one control group (n = 8) were root canal treated. After postendodontic sealing and build-up (AdheSE Universal, SDR), additional MOD preparations were cut. Postendodontic restorations were: Direct restorations (Tetric EvoCeram BulkFill bonded with AdheSE Universal and EverX Posterior/Essentia bonded with G-Premio Bond; as filling (F) or direct partial crown (DPC) after reducing the cusps 2 mm; indirect adhesive restorations (partial crown/PC vs. full crown/FC): e.max CAD, Celtra Duo, both luted with Variolink Esthetic; indirect zirconia restorations (partial crown/PC vs. full crown/FC), luted with RelyX Unicem 2; indirect non-bonded cast gold restorations (partial crown/PC vs. full crown/FC; Degunorm), luted with Ketac Cem. Before and after 300,000 thermocycles (5/55 °C) and 1.2 Mio. A total of 100 N load cycles, replicas were analyzed under a SEM for marginal quality in enamel and dentin (where applicable) and finally, specimens were loaded until fracture. Results: In direct groups, there was no difference between RC and FRC in fracture strength (p > 0.05); however, direct partial crowns showed higher post-fatigue fracture resistance. Regarding marginal quality, intracoronal FRC restorations exhibited more gap-free margins in enamel than RC. In the indirect groups, there was no significant difference between partial and full crowns in any of the adhesively luted ceramic groups regarding post-fatigue fracture resistance. Zirconia partial crowns exhibited significantly lower marginal quality in enamel. Indirect groups performed significantly better than direct groups in fracture resistance. Within the indirect restorations, both cast gold groups and zirconia full crowns exhibited the highest fracture resistance being superior to control teeth. Significances: Within the limits of this in vitro investigation, it can be concluded that any kind of indirect restoration with cusp replacement is suitable for ETT restoration when a certain cavity extension is exceeded. All indirect restorations, i.e., endocrowns, partial crowns, and full crowns showed a promising performance after in vitro fatigue-loading.

Onlays/partial crowns versus full crowns in restoring posterior teeth: a systematic review and meta-analysis

“…RD regarding the fracture of restorations proved it. In fact, we found out two in vitro studies comparing the difference of fracture resistance between onlays/partial crowns and full crowns [ 56 , 57 ]. Yu et al [ 56 ] investigated the fracture resistance and fracture modes of IPS e.max onlays and crowns, finding that ceramic onlays and crowns had the similar fracture resistance.…”

“…Nevertheless, mode II (less than half of the crown is lost) was the main fracture type of onlays restoring the endodontically treated teeth while severe fractures (Type V, a severe fracture of the crown and/or tooth) occurred mainly in the endodontically treated teeth restored by crowns [ 56 ]. Frankenberger et al [ 57 ] reported that no significant difference was found between the partial crowns and full crowns in the e.max group regarding post-fatigue fracture resistance. These laboratory outcomes were in agreement with our study.…”

“…Additionally, the material type also affected the fracture resistance of the onlays and crowns. Although IPS e.max onlays/partial crowns had the similar performance on fracture resistance when compared to the classical crowns, zirconia partial crowns exhibited significantly lower fracture resistance than full crowns [ 57 ].…”

Future Trends in Endodontics: How Could Materials Increase the Long-Term Outcome of Root Canal Therapies?

“…Nevertheless, the recurrent infection-related aspects are not the unique cause of long-term failure, since the mechanical fracture of endodontically treated teeth can occur [ 5 , 6 ]. As thoroughly demonstrated, the post-endodontic restoration of teeth with crowns or cast restorations does not influence treatment success based on periapical healing as long as there is no sign of coronal leakage; however, it can influence the survival rate of teeth over time, reducing the mechanical failure rate [ 7 , 8 ]. Despite this, the literature findings are still unclear regarding the relationship between the long-term outcome of RCT and the post-endodontic treatment plan with regard to the material of choice [ 9 , 10 ].…”

“…Firstly, the restoration should not interfere with the mechanical load of the tooth, protecting it from fractures arising from occlusal loads [ 6 ]. Secondly, the material should guarantee an intrinsic integrity and a good marginal adaptation over time in order to avoid leakage that could cause bacteria infiltration and the secondary contamination of the root canal system [ 7 ]. However, the most recent available data on the survival and failure rates of endodontically treated teeth according to the material used for the post-endodontic restoration in relation to the prosthodontic plan are still ambiguous, and clinicians often develop the treatment plan based on their personal judgment rather than on scientific evidence [ 12 ].…”